Spark plug



' v 4 H. W. STUVER SPARK PLUG Filed July 22, 1922 yParenteel @ca 2i, i924.

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HENRY W. STUVER, OF DENVER, COLORADO.

SPARK PLUG.

Application led July 22, 1922. Serial No. 576,793.

To aZZ wlw/m, it may concern.'

Be it known -that I, HENRY W. STUVER, a citizen of the United States, residing at Denver, in 'the county of Denver and State of Colorado, have invented certain new and useful Improvements in Spark Plugs, of which the following is a specification.

This invention relates to spark plugs'and its principal object is to provide a spark plug in which the electrodes and the parts with which their terminals are connected, are so formed and disposed as to reduce to a minimum the possibility of incapaci-tation by the collection of oil and carbon deposits.

Another object of the invention is to proyide a spark plug in which the electrodes are formed and relatively arranged so as to insure the production of a spark of maximum intensity.

With these and other objects in view, my invention consists in the construction and arrangement of parts illustrated in the-accompanying drawings in the various views of which like parts are similarly designated and in which- Figure l represents a partially sectional elevation of my improved spark plug; and

Figure 2, an underneath view of the same.

Referring to the drawings, the reference character 2 designates the screw-threaded metal shell or body portion of the plug, which in 'practice is fastened in a correspoilidingly threaded opening of the cylinder wal The shell has interiorly, a shoulder 3 for the support of the porcelain insulating core 4 which is secured in place by a retaining nut 5.

The shell is dished at its lower end as at 6, to provide a draining surface for the oil whic in the operation of the engine, splashes upwardly from the piston.

The lower end of the porcelain insulator extends beyond the end of the shell and it has a central recess vto receive the terminal of the inner electrode hereinafter to be described, and around said recess, a concaved thin rim 7 which likewise serves as a draining surface. Y, f

The inner electrode 8 which as usual, ex-

tends through a central passage of the in sulator and carries a binding nut 9 above l the upper end thereof, has a cup-shaped terminal 10 which fits inside the recess of the porcelain core and projects beyond the lower end thereof. The wall of the terminal tapers in thickness to itsedge where it is comparatively thin as clearly shown in the drawings.

The outer electrode 12 which as usual, is fastened at the lower end of the shell, is U-shaped and its free end extends into the cup-shaped terminal. of the other electrode in spaced relation to the inner surface thereof.

In the operation of the engine to which the spark plug is applied,the gas accumulating and conned inside the hollow terminal of the inner electrode, is ignited by the spark formed between the inner surface of said electrode and the corresponding portion 4of the other.

The thinness of the lower portions of the vcup-shaped terminal and the porcelain insulating body, causes them to be constantly in a glowing condition as long as the engine is in operation and thus prevents the accumulation of carbon between the electrodes byconsuming it immediately upon its formation.

The concave draining surfaces at the ends of the shell and the :insulator prevent carbon formation and fouling of the end of the spark plug by the downward flow of oil which enters the combustion space of the engine past the end of the reciprocating piston, and the entireplug being thus perlmanently kept in a clean condition, insures against short-circuiting of the current and assures a spark of maximum intensity at all times.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. A spark plug comprising a metal shell,

an insulating body therein, having at its lower end a recess and a thin rim around the same, an electrode having a cup-shaped terminal in said recess in spaced relation to the rim, and an electrode on the shell extending inside said cup-shaped terminal.

2. A spark plug comprising a metal shell,

an insulating "body therein, having ,at vits lower end a recess and a thin, downwardly tapering rim around the same, an electrode having a cup-shaped and downwardly tapering terminal in said recess in spaced relation to the rim, and an electrode on the shell extending inside said cup-shaped terl minal. v

3. A spark plug comprising a metal shell having its lower end beveled to provide a draining surface, an insulating body in the shell, extending through and below the lower end thereof and having at its lower end, a recess and a downwardly tapering rim around the recess and spaced from said bevdraining surface, an insulating body in the shell, extending through land below the lower end thereof and having at its lower end a recess and a thin rim around the same, an

electrode having a deep Acup-shaped terminal in said recess in spaced relation to the rim, and an electrode on the shell?-` having its end inside said cup-shaped terminal, the walls of said terminal and said rim being tapered in thickness to their lower edges.

lin testimony whereof l have axed my signature HENRY w. srnvnn. 

